1. Field of the Invention
The present invention relates generally to the field of stringed instruments. More specifically, the present invention is related to the field of improving the tonal characteristics of a guitar through structural modification.
2. Description of the Related Art
The typical acoustic guitar has a hollow body. The body defines a resonance chamber therein. The chamber is contained by a forward panel of the body. This panel is commonly referred to as a “sound board.” The sound board includes a hole. This hole is referred to as the “sound hole.” Connected to and extending back from the soundboard is a sideboard. This sideboard is completely closed off on its back edges by a backboard.
Typically, all of these components of the conventional guitar are constructed of choice pieces of wood. Composites or other materials may be used instead, however. The guitar also has a neck. One end of the neck is connected to the guitar body proximate the soundhole. The other end terminates in a headstock. On the headstock, one end of the strings are strung in a direction along the neck towards the body, and attached to a bridge. The bridge is fixed to the soundboard. It serves as an anchor for the other end of the strings. The bridge is placed such that the strings extend over the soundhole. The bridge typically includes a saddle. The saddle transfers vibrations in the strings to the soundboard. This results in the vibration of the entire soundboard.
The conventional soundhole is simply a circular cut out portion of the flat soundboard. When these strings vibrate above it, the bodily configuration of the guitar, including the resonance chamber cooperate with the soundhole to amplify the sound created by the vibrating soundboard.
It has been discovered that the sound of the guitar may be improved by constructing its soundboard, sideboard, and back of particular woods and/or composites. Various kinds and numbers of strings have been selected to alter its sound.
It is also known that the actual body design of the guitar is acoustically significant. Conventional guitars normally have a narrowed waist. One practical aspect of the narrowed waist is that it makes it easier to play for the user. This is because the narrowed portion is made to rest easily upon the user's knee. However, this design also affects the sound. The resulting two widened areas in the resonance chamber are called bouts. There is one bout where the neck connects, which is smaller. There is a second bout where the bridge attaches which is slightly larger. It is known in the art that the particular sizes and shapes of these bouts and their relativity to one another has much to do with the tone that the guitar produces. Thus, manipulation of the bouts and their shapes will cause a guitar to sound different. It has been discovered that the size of the lower bout—when optimized—accentuates the tones in the lower register of the instrument. And it is also known that ideal configuration of the upper bout accentuates the tones in the higher register when the instrument is played.
It has also been known in the art to reshape soundholes to affect sound. One example of this is U.S. Pat. No. 6,639,134 issued to Applicant. The '134 patent introduced a technique of modifying soundhole edge configurations to acoustically improve guitars, violins, and other like stringed instruments.
Need for improvement exists, however, in the way the soundboard, back, resonance chamber, and other features of the stringed instrument cooperate with the soundhole for acoustical purposes. As discussed briefly above, these components serve to amplify the vibrations received from the strings and release the amplified sound from the resonance chamber through the soundhole. But the waves at many frequencies tend to collide at locations proximate to the soundhole. This wave collision is detrimental in that it causes some sound waves to be propagated from inside the resonance chamber to leave the soundhole out of phase. This creates undesirable distortion, and limits sound fullness.